Electric-motor control.



E. W. PITTMAN.

ELECTRIC MOTOR CONTROL.

APPLICATION mcu MAR. 25. 1914.

Patented Aug. 7 1917.

WITNESSES &. 63A,), (7

' ATTOR r ERNEST W. PITTMAN, 0F FLUSHING, NEW YORK.

ELECTRIC-MOTOR CONTROL.

1,236,oo s.

Specification of Letters Patent.

Patented Aug. '7, 1917.

Application filed March 25, 1914. Serial No. 827,051.

To all whom it may concern 1 Be it known that I, ERNEST W. PITTMAN, a citizen of the United States of America, residing at 243 Jamaica avenue, Flushing, county of Queens, State of New York, have invented certain new and useful Improvements in Electric-Motor Controls, of which the following is a specification.

My invention relates to improvements in means for controlling the operation of an electric motor where same is employed as a source of power in driving an apparatus having moving parts where it is desired to regulate the speed of the motor according to the circumstances or conditions incident to the operation of the machine.

I will describe my invention as same is applied in the operation of a machine tool such, for instance, as a planer wherein a cutting tool is caused to engage the object to be cut or planed and in such operation to enter and pass through the material of which such object is formed and to leave the object when the cutting has been accomplished. In the operation of such machines there are several stages which it is desirable to note: first, that in the operation of the said machine the transfer from one cutting position to another be accomplished as rapidly as possible to conserve the time incident to such transfer; second, it is desirable that the cutting tool should enter the work at a speed preferably below the normal rate in order that the shock incident to such contact will be minimized; third, it is also desirable that the speed of the tool through the material acted upon should be proportionate to the resistance of the material; fourth, it is undesirable that the cutting tool should leave the material upon which it is acting at a higher rate of speed than that employed during its passage through the work, as the last fragment of the work is often not sufiicient to resist the cutting operation when accomplished at a high rate of speed, resulting often in a chipping or flaking of the edge of the material acted upon; fifth, it is also desirable in a reciprocating machine, such as a planer, to reverse the stroke ,after the tool leaves the work as speedily as possible and to restore the respective parts to their cutting position. It is the purpose of my invention to supply means by which these desirable results may be attained.

I have illustrated my invention in the accompanying drawing, wherein the figure is a dlagrammatic view illustrative of the operation of my invention, the parts being designated by letters and numerals, like characters and numerals referring to like parts.

I have elected to describe my invention as the same may be applied to a planer. I deem it unnecessary to illustrate the mechanical parts, all of which are well known and understood. I have therefore confined my illustration to a diagrammatic form, which I believe to be sufiicient to etficiently disclose my invention. I have desi nated the parts'by letters and numerals, re erring to like parts by like letters or numerals.

A represents a motor armature; B is the shunt field of the motor; C is the field rheost-at; D is a solenoid; E is the core of the solenoid D; F is the spring connected at one end to the core E and suitably anchored at the other end. G is a bridge mounted on the core E to move therewith. H is a series of contact points insulated from one an other and each connected to the corresponding point in the field rheostat. I is a bar contact; J is a bar contact; U is a series of contact points; 1, 2 and 3, K and L are solenoids, preferably located so as to act over the same region. M is a core for the two solenoids K and L, acting against a resistance such as the spring N, secured at one end to the core M and suitably anchored at the other end. The core M carries the bridge P, which moves therewith. S is a pair of contact points spanned by one end of the bridge G. T is another pair of contact goints spanned by one end of the bridge P. is a solenoid; R is a core for the same; R is a. cross bar secured to one end of the core R carrying the contact bars 36, 37 38 and 39. 1l11 are diagrammatic representations of the cutting tool such as is commonly employed in a planer; 25, 26, 27 and 28 are diagrammatic representations of brackets suitably mounted on some part of the planer, adapted to reciprocate therewith or to be acted upon by reciprocating objects. At the end of these brackets are pivotally mounted bell cranks 29, 30, 31 and 32, carrying at one end the rollers 21, 22, 23 and 24, and at the other end the contact points 14, 16, 18 and 20, to which are opposed corresponding contact points mounted on the brackets, same being designated as 13, 15, 17 and 19. 40 to 47, inclusive, are contact points. 49 is a bridgepivoted at50, and.51 1s a contact point. 'Secured to'the under side of contact point 14 is a knife spring 56 adapted in the rotation of the bell crank to :engage the vunderside of the rocker arm 49, and to--..retain such engagement until points 13 and 14 engage. 1212 is-a'figurative representation of two pieces of Work or two portions of the same piece of work set 'in'thepath of the operation of the planer, referred to hereinafter as the object or mate- 'rial'tol'be'acted on, the same having the surfaces 33 and34 bounded by aeontour 54 '54, '54", 1

1 will now describe the circuit connections. '1 is the armaturecircuit, the course of which is as follows :Beginning with the main line at X,lit traverses the course 1 "to the contact ,points 40 and 4", When it is desired to lead the current to theearmature to operate the same in one direction, the solenoid O is ener- ,g'ized, t'hus' lifting the coreR and the core bar R carrying the'contact bars 36 to 39, inclusive. Vith this operation the electrical connection is made. between the contact points 40 and 41 and the .current is led through the line 1 totthe armature; thence by .1 .to the contact point 42 .throughbridge 36'to the contact "point 43; thence by the line'l"; thence to the contact point 1, bridge P, contact bar J'to' the main line Y. If I desire'to lead'the current to the armature in the reverse direction and thus reverse the rotary-movement, I demagnetize the solenoid' O, which releases the-core 'R and permitsthe same to fall under the power .of gravity or otherwise, thus causing bar contacts 37 and 39 to span the contact points 44, 45, 46 and 47. The armature current will now flow in the line 1, contact point 47, ibridge 37, contact point 46, contact point 49. to the armature A, line 1, contact point 41, contact point 45, bar contact 39, contact ;point 44 to the main line through *1 as heretofore described.

Under certain conditions hereafter described, I divert the courseof the armature circuitand lead the same through the whole or part of the windings of the solenoid D to the contact points 2 and 3, and thus through the bridge P, and contact bar J to the main 'line.

'B 'is the field winc'ling; C is the field rheostat; C is the rheostat lever arm; H .are a series of contact points insulated from each other and connected to various points of the nheostat by the connections .jVhen connected by the bridge G with the-contact bar I, the circuit is made to (the armature circuit through 5, thus short circuiting one or more ofthe resistances of the. rheostat. (S is a shunt circuit short circuiting a predetermined number of the rheostat resistances.

such as the cutting tool and the work to be acted upon as in a laner, is well understood.

In the present device, the brackets '26 and 27 are so mounted with reference'to the work that the bell cranks 29t0 32, which are pivotally connected atthe end of said brackets, transverse the path of the operation of the machine in such relation to the surface of the work acted upon by the cutting tool that as they :traverse the-path of the tool or adjacent thereto, that they will impinge upon the surface of the object to becut-as 33- and '34 and in approaching said surface will be guided by the contour of said surface as '54, 54", 54", 54, '54. 49 is a bar contact suitably pivoted at 50. 51 is a contact point adapted to cotiperate therewith as the said bar is rocked on its pivot. 55 is a knife spring secured to the shaft 50 and freely connected with the bar 49 at 50 said spring operating to maintain said bar 49 in a normally horizontal position.

The operation of the bell crank levers in engaging the work and making and breaking the contacts to establish electrical circuits is briefly as follows :In the reciprocal movement of the machine from right to left, we will say, by Way of illustration, that the roller 21 engages ,the contour of the work at 54 and causes the rotation of the bell crank on its pivot 29 until it eventually rides on the surface 33, as illustrated with respect to the roller By this operation contact is made between the contact points 13 and 14. In like manner when the wheel 22 engages said contour of the Work to be acted on54, it is operated in manner similar to that described as the operation of the wheel 21,.and as a result contact points 15 and 16 are caused to engage, thus closing the circuit 48. \Vhen in the continued reciprocal movement of the machine in the same direction, 2'. e. from right to left, the rollers 21 and 22 leave the sur ace of the work and fall again to a vertical position, either under the power of gravityor otherwise, the-contactpoints 13 and 14 and 15 and 16 are separated and the c1ron it (48-77 )(4848-'7 (4887 is broken. When, however, the direction of the reciprocal movement of the planer is re versed, moving nowjfrom left to right, the roller 22 engages the opposite contour of the work at 54 lying in its reciprocating path and such contact operates to cause the hell crank 30 to rock on its pivot and in like niannel the hell crank 29 to rock until one arm thereof, to-wit the arm carrying the contact point 14:, operates to engage one. end of the pivoted contact lever 49 and to depress said lever.

throwing the sameout of the pathof the rotating arm 141 until that arm has described an arc beyond the arc of rotation of'thea-rm 49. The arm 49 is then restored to it's horizontal position by suitable means such, for instance, as a spring 55, when in the con: tinued reciprocal operationof the machine in the same direction the wheel 21 traverses;

the surface 33 and falls again into a vertical position, the rotation of the bell crank incident, thereto causes the end let of said bell crank to engage the end of the bar contact 119 operating to rock the same and bring it into contact with the contact point 51, thus closing the circuit (48-4S'- 7), thus rovers ing the motor as heretofore described. The knife spring 56 secured to the crank arm carrying the contact let is provided to engage the rocker arm 49 and retain such engagemer t temporarily while said'points13 and 14 are approachlng engagement, and to re lease the same ]L1St prior to such engagement.

And in the further rotation of the said bell lar machineqThe physical contact affectmg the operative members to make-or break the circuits hereinafter described may be accomplished by the engagement of any movn ing parts of theja'pparatus contact with any-other part" of the mechanism so long as'such contacts synchronize with the operations hereafter described.

The operation, of my device is as follows :'-]'n the primary or neutral position of theparts the bridge P is in-the position shown in dotted lines. 'at 52 and the wheel contact 23 is out of engagement wlth the work 12; that is to say, out of contact wlth the surface 3st. Under these conditions the solenoid O is demagnetized and falls under the power of gravity or otherwise and contact is made between the bar contacts 37 and 39 and the corresponding contact points at to 17, inclusive. Vi e will assume, therefore, that the cutting tools ].1--11 and the rollers 21 to Q-i, inclusive,

the work 12 at the time when the planer is i set in motion. The rheosta't lever C is also in its primary posltion. After starting the motor this lever C is thrown to its extreme position, as indicated in the drawing. ThlS "Mina M lw-inrr the machine tn Full peed When the circuit or mechanism inspedrof themotor by are" remote from The armature current flowing through. the circuit 1, contact point 47, bar contact-37, contact point 46, contact point 42, linel"; and then- 1, contact point 41, contact point 45, bar contact 39, contactpoint 44, line '1; thence to contact point 1 throughthebridge to the bar-contact J 'and-thenceto the main line Y. Assuming that the direction of the motor is to drive the work'toward the cutting tool, it will be seen 13115132811011 ath willhe traversed at the run speedo the motor. As the wheels 21'to 2etyare located in the path of the work, it will be apparent that the wheel as 21' willenga'ge the contour of the work as 54: and willv ride on the surface as 33, thus rocking the-bell crankon its pivot 29 and thus making contact between the contact points"13 and 14, and thereby closing the circuit (18-45-7 The position last described is diagrammatically shown in the position of the wheel 23 with reference to the surface of-the work. I

In the latter case the circuit 9 is made :by the contact illustrated. The operation of the circuits (487"-7 (48 -48 4 (48- 87) isidentical with 9 and 10except in that the former are in series? with circuit 48; consequently a description of one will suffice for the others. IhQ OII'lY-I'BRSO DITOI having two .sets of circuits 'is to provide a reater pull on the'jcore M, for the purpose of transferring the bridge 'P'jiII its respective'relation to the contact points 1. and-*2 and3, for purposes which "will more fully described; 1 n

i (4:8,7'-7) is made-as stated, by reason of the contact-between the .roller 21 and the work, the solenoid K is energized, thus operating'tojmove the core M, and consequently the "bridge P mounted" thereon, against the power eithe -spring N, that is to say, from -its primary posi-' 1 tion, as shown in dottedlines'at 52i togits secondary position as shown in "fulllines,

' This operates to'close the gapT and make I the circuit 6. It also operates to break'the contact at 1 and" make the, similar contact at 2, thus leading the armature circuit through the entire length of the solenold D,

behereafter through the bridge P, ba'rcontactJ to the '115 main line. The making'of thejcircuit Goperates as aishunt to cut out a portion ofthe rheostat and hence slowdown themot'or.

The amount of the resistancecut' out'by this shunt may be predetermined "and'hence the this means may "be regulated at a predetermined rate. prefor that the rate should he reduced 'to a point somewhat belowxthe normal rate of the operation of the cutting toolas it passes through the work. The pur ose/ r uin slowing down the motor is to bring 'the' tool to the work atv a reduced speed. Ifind it to be desirable that the tool should enter the work under these conditlons.

' material to. be cut, also the size ofthe cut.

the cutting tool often 'va'jries after the tool 'due to the pressureexerted by thev tool. I

As soon 'asthe @111 entersthe work, a.

physical resistance is opposed to its'operahas entered the, work, and during its path through the material, dependent upon the] nature of the material, which often presents hard spots which ofier greater resistance to the tbel, so that it will be understood that there is a possibility of a varying resistance to the operation of the tool from the begin nmg to the-end of its cut. I have also ob served that as the tool approaches the contour of the workpieparatory to leaving the same, suchcontour is apt to flake off or chip,

find it desirable, therefore, to control the speed, of the motorto meet these conditions. This is accomplished by the employment of a wheel as 22, which is intended to follow the tool through the work but still retain its connection with the surface of the work 'until the tool has passed completelv through the same, thus operating to prevent-the mo- .tor from speeding up while said wheel 22 remains in'contact with the work.

To recur now to 'theoperation which was incident to the closing of the circuit (48.7'7),' it will be recalled that the bridge P was transferred from the contact point 1 to the contact point 2, audit will be recalled that this adjustment made the armature circuit. through the solenoid D. Under theplan of adjustment which I here propose, it is intended that the tension of the'spring F shallbe sufli'cient to overcome any magnetic force that may be generated in the solenoid D by reason of the passing of.

the armature current through the coils of that solenoid, prior to the engagement of the tool, thus retaining the bridge G in-its primary position. As soon, however, as the work 12 engages thetool 11, a resistance to' the movement of the -parts is presented,

which is immediately translated into an additional load on the motor thus causing a.

armature current is again reduced so that flow of current proportioned to theload,

With this increase of current agreater mag-- netic force is generated in the soleno1d D and the core is afl'ected thereby, suchforce being sufficient to overcome the fixed tension of the spring F operating to draw the core E and the vbridge G carried thereby toward the solenoid D, thus opening the gap S and thereby'breakingtlie circuit 6 and at'the same time making con'tact between oneof the insulated contact points H and making one of 'theshunt circuits 5 through the rheostat C. It will, therefore, be understood that with the varying load on themo tor the mag netic force in the solenoid D will vary proportionately and in' a like manner therec ip rocating movement of the core will estabhsh ception'that one 'K, and solenoid or the shunt circuits through the rheostat C, thus varying 'the-.resistance and.

consequently the spe'edlof the motor. lt'will, of course, be understood-that-the degree of movement of said rheostat control will be dependent on the amount-of pull exercised by the spring F and that such pull my be variable and adjustable according ,to a pre determined rate ratio between the. current" trol of the solenoid D in combination with the spring F, it beingundersto'od that the operation of these elements is dependent on the current and the current ongthe load. An accurate proportion may be here established dependent upon well known mechanical and electrical conditions and, as previously stated, the speed of the tool through .the work will be regulatedaccording to the resistance presented to the tool. I

In the reciprocal operation of the laner, it will be obvious that the wheel 21 wil leave the work'beforethe tool has completed its cutting operation, but I prefer to so arrange the relations between-the wheels 21 and 22 so that the wheel 22 :will be in contact withthe work at the time when the wheel 21 has left the same. By this latter contact, it will 'be'understood that I establish-the circuit 7 by uniting the contact points 15 and 16, so that notwithstanding the fact that the wheel 21 has run ofi'the work and the contact be-v tween the contact points 13 and 14 is broken,

. still the parallel circuit '(48' '8-'7-) will be maintained and the same results follow until "the tool has entirely traversed and left the work. thebtbolleaves the work-the when said shunt 6 is immediately-broken and'the'motor'proceeds at full speed ahead. I have illustrateda plurality of tools and also a. plurality of rollers making contact with 'the surface of the work. Their elec.'

trical operations correspond. with the e tgoup control the solenoid I while the other group control the solenoid L, both operating in the same field and on the samecore M. My

. of the machine may be said'to be in the 0011- I purpose in this is to.provide means for cutting out a number of the turns of wire of the solenoid D, where the balancing of its magnetic resistance against the mechanical resistance F is desired, and to maintain at all times the relation between the operating parts which shall be under the control of a member contacting with the surface of the work. The operation of this mechanism is as follows: Where one or more of the wheels controlling the shunt circuit 6 are in contact with the surface of the work, said shunt circuit will, be maintained unless broken at the point S. Where there are a plurality of tools operating and in the balancing of the load against the resistance above described, I desire to cut out a part of the solenoid D when an additional tool is brought into operation, I provide the secondary circuits 9 and 10 leading to the solenoid L. If the circuits (l87-7) or (l8-87) are closed at the same time with either of the circuits 9 or 10, both of the solenoids L and K will be energized as opposed to the spring N, and as their magnetic force is assumed to be equal, it will be apparent that the pull on the core M will be doubled, thus operating to move the bridge P from the contact point 2 to the contact point 3*, thus leading the armature circuit through only a part of the solenoid D as at 3, thus reducing the number of turns in D when the strength of the current in D is increased and keeping the maguetidforce of D constant. This operates to keep the cutting speed the same whether one or two tools are in operation. This same result may be accomplished by mechan ical means such as regulating the tension of the spring F according to a predetermined ratio as heretofore stated.

In the foregoing description I have assumed that the planer was moving in one direction. It is desirable that such direction should be reversed as speedily as possible after the tool has left the work, thus econo mixing the time incident to the removing of the work from one operative position to another. This I accomplish as follows: During the period that the wheel '21 or any other of a plurality of wheels operating the same mechanism is in contact with the work, the circuit (lS-77) is made by reason of contact between the contact points 13 and 14. This circuit operates to energize the solenoid O and lift the core It, making contact with the contact points 4-0 to 43, respectively, and giving the motor a rotary motion in one direction. As soon as the wheel 21 or the last of a plurality of wheels operating in a similar manner leaves the work, the circuit (et87-7) is broken by the fact that the bell crank is turned on its pivot 29, the lower arm of the bell crank assuming a vertical position, thus breaking the contacts 13 and 14, and the contact bar 1} falls under the power of gravity or otherwise and makes contact between the contact bars 37, 39 and the contact points 44 to 47 inclusive, thus causing a delivery of current to the motor in an opposite direction and hence a reversal of its rotation. This reverse movement of the motor will, of course, develop a reverse reciprocal movement in the planer and the wheel 21 or any one of the wheels of a kindred nature and in a similar position will engage the opposite side of the work as at the point or contour 54 incident to the re ciprocal movement and travel over the same path on the face of the work as it had previously traveled in the opposite direction, the result being that the bell crank, one end of which is connected with said wheel 21, will be turned on its pivot 29 describing a more extended arc than that of its previous motion, causing the back side of the opposite arm to engage and pass behind the pivot contact bar 49, as shown in dotted lines, it being understood that the contact bar 49 is pivotally connected at 50 with a suitable spring to restore the same to its normal position after the arm of the bell crank has passed beyond contact therewith. I have indicated such a spring as 55. As the roller passes off of the surface 33, at the contour 54, it falls into a vertical. position by the power of gravity or otherwise and in so doing its opposite arm engages the pivotal contact lever 49 causing the same to make contact with the contact point 51 thus again completing the circuit (48-48 and. en ergizing the armature 0, thus lifting the core R and makin the contacts to establish the armature circuit in the reverse direction. This, of course, operates to reverse the reciprocal movement of the planer. Then all of the steps previously described are repeated again and again.

I have stated that those incidents applicable to the operation of the rollers 21 to 24 are the same. This is true with the exception that in operating a reciprocating machine, I confine the means for reversing the motor to the wheel following the tool. It will be understood that in all of the operations above described, I have dealt with them theoretically and illustrated them diagrammatically. I do not intend to limit my claims to any specific form of mechanism either mechanical or electrical so long as the fundamental principles disclosed herein are utilized.

From the foregoing it will be apparent that by the means stated, I am able to shift the work from one operative position to another when not in engagement with the tool at the maximum speed of the motor, to slow down such speed as the work approaches the tool, to. regulate the speed during the course of its operation through the work de endent on the resistance offered by the wor to the tool, to control the-speed at which-the=tool finally escapes fIOIIlE the workafter the load is either wholly or partly lifted from the motor, sufiicientat all events to throw thecore E back again intothe power of the spring F and thus restore the-shunt circuit: 6, to reverse the motor as soon as-the last 0f= the contactwhee1s= 21' to 24-leaves the work, to again-reverse the motor as soon as-the contactwheels-Ql to 24, or the last of: them, leaves the work and so continuously tooperate the planerg to reciprocate and-to causea reverse movement! of the planeradjacent. to the contour or edge of the horizontal lane of thesurface of the work. It will he apparent,therefore, that no matter what this contour; may be, whether of regular orirregularform, whether inonerposition oranother with reference to the-tool, the reverse. movement will be accomplished as soon as; the lastroller, leaves the SllI'ftLCGrOf; the work adj acent! itscontour.

I{ have illustratedi the tools: 1-l11-- and? brackets 25 to 28 as in tandem; lnatheiop eratiornof-x a planer these elements would be mounted-to reciprocate in parallel;paths,.but: they wouldi bemounted in=.a plane at right: angles to such path. This is-.my: purpose in the illustration but it will be-understoodathat their position-.may be v-aried'to any position consistent withthe operation that I have described.-

Where I have :referred to arheostatas an element! in this specificationandi claims, L desire. to have the same understood" in its generic sense, .to indicate any means adapted to control the speed of the motor through. a variation of the magnetic efiectiofa itsfield on the armature of the motor.

What I claim is 1. In an-apparatus ofthe class described, a motor, a rheostat interposed? in the field circuit, a machine tool having partsmoving in a prescribed path, adapted to operateupon asuitably mounted'object which hasa contour comprising a surface operated upon by. saidtool, means carried by said machine tool=and controlled by contact with the saidsurface as the path of its operationis tray-- ersed-to control a shunt circuit through saidrheostat,-.thereby regulating the speed of the motor. and means to break! said lastmentioned shunt circuit when the motor is subject to the load andrestore the-same when relieved of: the load.

2. In an apparatus of the class described, a motor, arheostatinterposed in thefield circuit, a machine tool havingparts moving in aprescribedpath, adaptedt'o operateupon a suitably. mounted object which has:a contour comprising asurface operated upon by: said tool, means carriedby said machine a tool and controllediby contact-*wit-h-thesaid? surface as-the path of its operationis-ltravas. arsed,t ncontrola-tshuntlcircuitithroughisaid naaepos r-heostat, thereby. regulatinggthe speed of the moton and meansto brea said last mentioned shunt-circuit when the motor is subject to the load and restore the same when-relievedofi the load, and means to control the direction of the drive controlled by the disengagementbetweenthe surface of said object according to its contour and said speed controlling-- means which iscontrolled by contact with-.thwsurface of theobjectn 3. In an apparatusof the classdescribed, amotor, a rheostat interposed in thefield circuit,,an' armature circuit in which is included azsolenoidzwith aicore, means to regulate the -movement of said core as opposed to'the-operation of the magnetic force act ingi thereon, throughsaid solenoid; according; to the load on the motor, means to -control: the-rheostat; operated by the movement of? the core, amachine tool; having parts moving: in aprescribed path, adapted to;

operate upona suitably mounted object WilliCli-llflfizih contour comprising a surface operated: upomby saidetool, meanscarried bysaid' machine tool and cont-rollediby contact with the said surface as the path of its-operation-iis traversed-to control a shunt circuiti through; said rheostati thereby regulating the speed of; the motor and means operated by-saidzcone' to make or break saidlast mentioned circuitt.

4t.v Inan apparatus of theclass described,

a; motor,v a. nheostat interposed in the field circuit, an: armature circuit inwhich is:included a solenoid with a core, means to regulatethe movementxof said core as op posedto the operation of: the magnetic-force acting; thereom. through said solenoid according to the load on the motor,,means to control the rheostatoperated by the movement of thecore, a machine tool havin parts. moving. in aprescribed path, adapte to, operate upon a suitably mounted object which has a contour comprising a surface operatedupon=by said tool, means carried:

by said machine tool and controlled by contact with the said surface as the path of itsoperation istraversed to control a shunt circuit. throughsaid rheostat thereby regulating: the. speed of; the motor and means op erated by said core to makeor break saidlast mentionedicircuit andmeans to control the direction'of the drive controlled by the disengagement, between the surface of said object according to its contour and said speedcontrolling means which is controlledby contact with the surface of the object asstated;

5. In an apparatus of the class described, a; motor, arheostat interposed in the field circuit, an armature circuit in which is included a solenoidwith a core, means to lead said armature circuit through more or less Ofthe helix-ofsaidisolenoid, means to regu? late the movement. of, said; core as opposed to the operation of the magnetic force acting thereon through said solenoid according to the load 011 the motor, means to control the rheostat operated by the movement of the core, a machine tool having parts moving in a prescribed path, adapted to operate upon a suitably mounted object which has a contour comprising a surface operated upon by said tool, means carried by said machine tool and controlled by contact with the said surface as the path of its operation is traversed to control a shunt circuit through said rheostat thereby regulating the speed of the motor and also to control the course of said armature circuit through more or less of the windings of said solenoid according to the load on the motor, and means operated by said core to control said shunt circuit. through said rheostat which as stated controls the speed of the motor.

6. In an apparatus of the class described, a motor, a rheostat interposed in the field circuit, an armature circuit in which is included asolenoid with a core, means to lead said armature circuit through more or less of the helix of said solenoid, means to regulate the movement of said core as opposed to the operation of the magnetic force acting thereon through said solenoid according to the load on the motor, means to control the rheostat operated by the movement of the core, a machine tool having parts moving in a prescribed path, adapted to operate upon a suitably mounted object which has a contour comprising a surface operated upon by said tool, means carried by said machine tool and controlled by contact witli the said surface as the path of its operation is traversed to control a shunt circuit through said rheostat thereby regulatin the speed of the motor and also to control the course of said armature circuit through more or less of the windings of said solenoid according to the load on the motor, and means operated by said core to control said shunt circuit through said rheostat which as stated controls the speed of the motor and means to control the direction of the drive controlled by the disengagement between the surface of said object according to its contour and said speed controlling means which is controlled by contact with the surface of the object as stated.

7. In an apparatus of the class described, a motor, a rheostat interposed in the field circuit, a machine tool having parts moving in a prescribed path, adapted to operate upon a suitably mounted object which has a contour comprising a surface operated upon by said tool, a member phivotly mounted and carried by said mac ine tool and operating in the path of its movement to engage and disengage the said contour and surface acted on by the tool and by suchcontact rocked on its pivot, means controlled by the rocking movement of said member to control the field circuit through said rheostat and thus regulate the speed of the motor, and means to break the circuit thus controlled by said rocking movement when the motor is subject to the cutting load and to restore the same when relieved of such load.

8. In an apparatus of the class described, a motor, a rheostat interposed in the field circuit, a machine tool having parts moving in a prescribed path, adapted to operate upon a suitably mounted object which has a contour comprising a surface operated upon by said tool, a member pivotally mounted and carried by said machine tool and operating in the path of its movement to engage and disengage the said contour and surface acted on by the tool and by such contact rocked on its pivot, means controlled by the rocking movement of the said member to control the field circuit through said rheostat and thus regulate the speed of the motor, and means to break the circuit thus controlled by said rocking movement when the motor is subject to the cutting load and to restore the same when relieved of such load, means to control the-direction of the drive of the motor controlled by the rocking of the said member as it engages or disengages the contour and surface of the object.

9. In an apparatus of the class described, a motor, a rheostat interposed in the field circuit, an armature circuit in which is included a solenoid with a core, means to regulate the movement of the said core as opposed to the operation of the magnetic force acting thereon through said solenoid according to the load on the motor, means to control the rheostat operated by the movement of the core, a machine tool having parts moving in a prescribed path, adapted to operate upon a suitably mounted object which has a contour comprising a surface operated upon by said tool, a member pivotally mounted and carried by said machine tool and operating in the path of its movement to engage and disengage the said contour and surface acted on by the tool and by such contact rocked on its pivot, means controlled by the rocking movement of the said member to control the field circuit through said rheostat and thus regulate the noid with meansitolead said circuit, through:

more or less of the windings of said core, av core for saidsolenold, means to regulate the movement of said core as opposed to the operation of the magnetic force acting there 2m membersto-control the field circuit through said rheostat and thus regulate the speed of the motor during the period when the tool is approaching or leaving the work, and. meanscontrolled. by the movement of the core of the solenoid to break thecircuit undercontrol of. the last mentioned means when thetool enters the work and during theperiod that the motor is subject to the cutting load, but to restore the same when the cutting operation is concluded, and means-alsooperated by said rocking members as the same are pivotally operated by contact with the surface of said object or disengagement therefrom to control said means to lead the armature through more or less of. the solenoid windings. the same dependent on the number of rocking members in or out of engagement with the surface of the object being acted on by the cuttingtool or tools..

11. In an apparatus of the class described, a machine adapted to exert power, a motor to drive said machine, a rheostat interposed in the field circuit of said motor and a solenoid interposed in its armature circuit, said solenoid. having a core, a resistance opposed to the movement of said core proportioned to the magnetic force developed in the solenoid according to the load on the motor, means controlled by the movement of said core to operate the rheostat and thus control the speed of the motor, means operated by engagement between moving parts of the electrically driven machine to control the rheostat before said solenoid is energized and after the same is de'energized.

12. In an apparatus of the class described, a machine adapted to exert power, a motor to drive said machine, a rheostat interposed in the field circuit of said motor and a sole noid interposed in its armature circuit, said solenoid having a core, a resistance opposed to the movement of said coreproportionedito the magnetic force developed in the-solenoid according to the load on the motor, means controlled by the-movement of: saidcoreto operate the rheostat and thus control the speed ofthemotor, means operated by en gagement between moving parts of, the electrically driven machine to control current to the motor. to control the direction ofits operation.

13. In an apparatus of the class described, a machine adapted to exert power, a motor to drive said machine, a rheostat interposed in the field circuit of said motorand. a solenoid interposed in its armature circuit, said solenoid-having a core, a resistance opposed to the movement of said coreproportioned to the magnetic force developed in the solenoid according to the loadon the motor, meanscontrolled by the movement of said core to operate the rheostat and thuscontrol the speed of. the motor, means operated by engagement between moving parts of the electrically driven machine to control current to the-motor to control the direction of its operation, means operated by engagement between moving partsof the electrically driven machine to control-the rheostat before said; solenoid'is energized and after the same isdeenergized.

14. In an apparatus-of the class described, a machine adapted. to exert power, a motor to drive said machine, a rheostatinterposed in-the field circuit-of said motor and a solenoid interposed-in its armature circuit, said solenoid having a core, a resistance opposed to the movement in the solenoid according to the load on; the-motor, means controlled by the movement of: said core to operate the rheostat and thus controlithe speed of the motor, means operated by engagement be tween moving par-ts of-the-electrically driven machine and a suitably mounted object which has a contour comprising a surface operated upon by said machine to control current to the motor to control the direction of its operation, means operated by engagement; between moving parts of'the electrically driven machine to control the rheostat before said solenoid is energized and after the same is deenergized, means operated by engagement between: a plurality ofmoving parts of said electricall driven machine and a suitably mounted ob ect which has a contour comprising a: surface operated upon by said. machine to control the degree of magnetic force in the solenoid.

15. Inan-apparatusof the class described, a motor,- a rheostat interposed in the field circuit, a: machine tool having'parts-operating in a prescribed path, an object suitably mounted to be operated on by said tool as it moves in said path, said object having a surface to be-acted on by said tooland means carried by saidmaehine tool and controlled by contact with the surface of said object as the path of its operation is traversed to control a shuntcircuit through. said rheostat thereby regulating the speed of the motor.

16. In an apparatus of the class described, a motor, a rheostat interposed in the field circuit, a machine tool having parts moving in a prescribed path adapted to operate upon a suitably mounted ob]ect, an object suitably mounted in the path of said movement, said object having a contour comprising a surface operated upon by said tool, means carried by said machine tool and controlled by contact with the surface of said object as the path of its operation is traversed to con trol the direction of the current to the armature, thus determining the direction of rota tion of the motor.

Signed by me at New York this 21st day of March, 1914:.

ERNEST W. PITTMAN. Witnesses: CHARLES D. EDwARns,

MARGARET V. Voonn.

Copies 0! this patent may be obtained for live cents each, by addressing the "Commissioner of Patents,

Washington, D. 0." 

